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HOG'S FAT

421

The physical and chemical characters of oleomargarine are :

Specific gravity at 15°

,,    98-100°
Melting point   ....

,,           ,,    of fatty acids

Solidifying point of fatty acids.
Zeiss refractometric reading, at 35°   .

„   40°   •

Acid number, if fresh and well stored
Saponification number
Iodine number.         .         .         .         .
Fixed acid number   ....
Volatile ,,         ,,....

.     0-924-0-930
0-859-0-863

32-35° (sometimes up to 40°)
. 40-43°
.. 39-42°

•    47-49

o

192-200 (195-198)
42-55 (43-48)

•      95-96
.   o -4-1 -o

Under the polarising microscope it behaves like fused butter (see 3 in article
on Butter, Vol. II, Chapter II).

HOG'S  FAT

Hog's fat is, strictly speaking, the fat of the inside of the animal, that
adhering to the inside of the skin constituting lard.

American hog's fat is divided into various qualities according to the
method of preparation.

In general the fat is white and pasty, with a peculiar odour and a sweetish
taste ; it becomes rancid easily, turning yellow. It is only slightly soluble
in alcohol. With the ordinary reagents for oils it gives no colour reactions.
Its characters are given in Table XLVII.

Detection of Adulterations.—Lard is adulterated with or ^even replaced
by mixtures of tallow, pressed tallow (also hardened or hydrogenised oils),
cottonseed stearine or other vegetable fats, or cottonseed, sesame, arachis,
maize, sunflower-seed, coco-nut or lard oil; also with pressed lard and
vegetable oils. The artificial mixtures constituting lard substitutes often
contain a small proportion of lard, recognisable mainly by its characteristic
odour. Lards containing marked amounts of water, incorporated with
the help of a little alkali, are also found.

The various adulterations are detected as follows :

1.  WATER, ALKALI AND OTHER MINERAL SUBSTANCES.   The water is
determined by drying the fat at 100° to constant weight.   Alkalis and
other mineral matters may be found by incinerating the fat and examining
the ash ; the former may also be detected by treating with hot water and
testing with litmus paper, or by passing a current of steam for half an hour
into a mixture of 60 grams of the fat with 60 grams of water, then allowing
the mass to cool and filtering : in presence of an alkali or an alkaline earth,
a milky filtrate is obtained.

2.  TALLOW, PRESSED TALLOW OR OTHER ANIMAL FAT OR HARDENED
(HYDROGENISED) OIL.    These substances are tested for by Earner's method,'1

1 Zeitschr. Unt. Nahr. Genussmittel, 1913, XXVI, p. 559- See also papers on this
method by Bomer, Alpers, Fischer and Werwerinke, and Sprinkmeyer and Diedrichs
(ibid., 1914, XXVII, pp. 142, 153, 361, 571).ermometer noierl.